Various efforts in the past have been made to provide relatively low cost, lightweight insulating sleeves knitted, woven or braided of glass fiber or other insulating yarns for the purpose of insulating elongated tubes and similar elements. A need arises in the automotive field in the insulation of very high temperature devices, such as exhaust gas recirculation devices. The high temperatures generated by such devices are potentially damaging to other automotive components and, if the devices are not isolated, have been known to ignite combustibles if, for example, the automobile is parked in a field of dry grass.
Although sleevings of the type sold by The Bentley-Harris Manufacturing Company under the trademarks THERMFLEX and THERMFLEX SPIRAL are effective for many applications, there are occasions where an unsatisfied need still persists for a cost effective solution to the need for the protection of components from the deleterious effects of heat generated in modern high-performance vehicles.
The THERMFLEX SPIRAL product referenced above is a flexible, smooth, compactly braided sleeve which is braided from glass fiber yarns. In the THERMFLEX SPIRAL product, a spiral cord of relatively large diameter stands the insulating sleeve off from the substrate, creating an air gap in order to increase its insulation properties. Although this product solved the problem to a degree, the air gap provided is not as great as is desired for many applications.